Vehicles are traditionally powered by engines which provide drive for the vehicle and batteries, which provide power for starting the engine and for vehicle accessories. The vehicle systems and accessory systems generate heat and require cooling. Fluids are typically pumped from a fluid source to cool and lubricate these components. In the process, the fluids themselves absorb heat from the components they are cooling. When the fluid is returned to the fluid source there may be uneven heat distribution among the returning fluid and the fluid that is already in the fluid source. For example, the transmission fluid is heated as it is used to lubricate and cool the transmission. However, the heat distribution of the fluid within a transmission sump is often uneven. Uneven heat distribution within the fluid source may lead to less efficient cooling of the associated vehicle system.